The present invention relates generally to locking systems and methods for rotary closure assemblies. More particularly, the present invention relates to a locking closure system and method for a lug type locking arrangement that includes a pressure warning release screw device.
In fluid or gas handling systems in industry, particularly pressurized systems, it is known to provide a so-called closure assembly to provide quick and safe access into some part of the interior of the fluid or gas handling system. For example, in the gas and/or chemical industries, it is common for there to be various pipelines and vessels that generally operate in a pressurized environment. When the systems are not in operation, it is often desirable to have access to the inside of the systems for cleaning, inspection, and/or the changing of filters or other replaceable elements which may be present.
Some applications of closure systems include those in the petrochemical, pharmaceutical and chemical process industries such as blow downs, manways, meter provers, filters, strainers, coalescers, waste disposal vessels, and autoclaves. Typical closures may for example range in diameter from 4 inches to 24 inches, with working pressures up to ANSI 300 (740 psi/51.1 bar) and temperatures from xe2x88x9250 degrees F. to 400 degrees F.
One approach to providing a closure is to provide a flange around an opening at the end of a hub-shaped extension that extends from some part of the fluid handling system. A covering or closing element, which forms a cap often referred to as a head, and which may simply be a disk shape or a dome-shaped piece of material, is removably but securely attached over the flanged opening to provide a fluid-tight and pressure-tight seal when closed. The cover is removable to provide access to the interior of the pressurized system via the opening in the flange.
One way of securing the cover element, or closure, onto the flanged opening has been simply to provide a series of corresponding bolt holes through the cover and around the circumference of the flange so that individual bolts may be inserted through the corresponding holes and tightened. Tightening the bolts presses the circumference of the closure against the flange, and a sealing element such as a gasket may be provided between the closure and the flange. Tightening all the bolts provides closing pressure and a seal at the gasket to resist escaping of the fluid or gas daring system operation. A disadvantage of these bolt type closures is that individually installing and/or removing bolts can be time consuming and cumbersome, particularly where a large number of bolts are required.
Another type of closure is the so-called screw type of closure, in which the flange has a threaded outer surface, and the closing element is shaped like a cap and has a corresponding threaded inner surface. This closure is screwed onto the flange to provide a seal. A disadvantage of screw type closures is that closing the cap usually requires that the cap be rotated many degrees, even several rotations.
A third type of closure is the so-called rotary lug type closure. In this arrangement, the outer circumference of the flange has several lugs projecting outwardly, and the cover or head has grooves and corresponding lugs projecting inwardly. Thus, the head can be oriented at an angle where it can be pushed axially onto the flange. The head can be rotated a specified number of degrees so that the lugs interfere with each other and prevent the head from moving axially. In this arrangement, once the head has been rotated so that the lugs are fully interfering, the head is held pressure-tight against the flange, to resist leakage and pressure.
Lug type rotary systems can be preferable to screw type systems because the cover can be moved from a fully openable to a fully closed position merely by rotating the cover by a partial turn, e.g., by 45 degrees. This can be a more simple operation than the many rotations sometimes required on a screw type closure.
Industrial systems often handle fluids and/or gases at very high pressures. Before accessing these systems via a closure, it is generally known to depressurize the system by means of a main bleed valve located somewhere in the system. It is be desirable to have a safety device to prevent opening of these closures where significant pressure exists inside the system, for example as would occur if the main bleed valve operation has not been performed. Since these systems sometimes have residual pressures even after the main bleed process has been performed, it can also be desirable for the closure to have some type of safety device to prevent opening of the closure even when a residual internal pressure is present. It may sometimes also desirable to have some arrangement for bleeding out these residual pressures at the location of the closure, so that pressure at the closure can first be bled out, and then opening of the closure can be effected, all at the location of the closure. Thus, there is a need for a system and method that (1) provides a warning to the operator of full and/or residual pressure and/or (2) releases pressure in the region of closure, before the closure can be opened.
It is therefor a feature and advantage of the present invention to provide a system and method that (1) provides a notification to the operator of full and/or residual pressure, and/or (2) releases pressure in the region of closure, before the closure can be opened. The above and other features and advantages are achieved through the use of a novel system and method as herein disclosed. In accordance with one embodiment of the present invention, an apparatus for locking a closure assembly in a closed position has a hub having an opening therethrough; at least one hub lug projecting from the hub; and a head having at least one hub lug projecting therefrom. The head is rotatable between an unlocked position where the lugs do not interfere with each other and the head may be removed from the hub, and a closed position where the lugs at least partially overlap each other and interfere with each other so that the head is held in a sealing engagement with the hub. A vent bore passes through at least one of the head and the hub; and a first locking bore passes through the head. A second locking bore extends at least partially into the hub and is aligned with the first locking bore when the head is in the closed position. A seal and lock device includes a sealing element that releasably seals the vent bore and a projection that projects into the first and second bores when the head is in the closed position and the sealing element is sealing the vent bore.
In another aspect the invention provides a releaseable locking element movable between a locked position that locks the head in a closed position and an unlocked position. A pressure warning device is movable between a sealed position and a warning position and is operably connected to the locking element so that the pressure warning device must be in a warning position in order for the locking element to be unlocked.
In another aspect, the invention provides a releaseable locking element moveable between a locked position which locks the head in a closed position, and an unlocked position. A pressure warning means is moveable between a sealed position and a warning position, and is operably connected to the locking means so that the pressure warning means must be in a warning position in order for the locking means to be unlocked.
A method for locking a closure assembly in a closed position for use with a hub having an opening therethrough and a head removably attachable to the hub via a lug-type holding arrangement. The method includes moving a pressure warning/release device from a sealed position to a warning position, the warning/release device operably connected to a locking device that operates to withdraw a projection from the lug-type holding arrangement, so that the pressure warning/release device must be in a warning position in order for the locking device to be unlocked.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.